1. FIELD OF THE INVENTION
The present invention relates to an IC card module, and, more particularly, to an IC module (abbreviated to "module" hereinafter) designed to be mounted on thin semiconductor devices such as IC cards.
2. DESCRIPTION OF THE RELATED ART
FIG. 1 is a side elevational cross-sectional view which illustrates a conventional module to be mounted on a thin semiconductor device such as an IC card. Module 1a includes: a circuit substrate 2 on which a circuit 1 is formed; an IC chip 4 secured to the surface of the circuit substrate 2 by means of a die bonding material 3; and sealing resin 5 for sealing both the IC chip 4 and the portion around the IC chip 4.
Furthermore, the conventional IC card module 1a is structured in such a manner that a connecting terminal 7 is provided on the reverse side of a substrate core 6 of the circuit substrate 2, this connecting terminal 7 being electrically connected to the circuit 1 disposed on the obverse side of the substrate core 6 via a conductor 8 enclosed in a through hole 8a. The IC chip 4 and the circuit 1 disposed on the surface of the circuit substrate 2 are connected to each other by a metallic wire 9 or the like whereby a connection portion 10 is formed, and a portion in the vicinity of the IC chip 4 including this connection portion 10 is sealed by a sealing resin 5 such as epoxy resin.
The circuit substrate 2 of the IC card module 1a cannot be subjected to relatively high temperatures since the same comprises, for example, a glass epoxy printed circuit substrate. Thus, the types of material that can be used as the die bonding material 3 for die-bonding the IC chip 4 are limited. In addition, the conditions for wire-bonding the circuit 1 on the circuit substrate 2 to the IC chip 4 using a metallic wire or the like are also limited. Furthermore, since the IC chip 4 is not packed with a resin, the module 1a before being resin sealed need to be manufactured in clean rooms or the like. This leads to the fact that the yields obtainable in manufacturing the module 1a are low and that the final products lack satisfactory reliability. In addition, the work of sealing IC chip 4 with resin raises a problem of poor working efficiency and dimensional stability due to the fact that the sealing with resin is performed by potting. If this resin-sealing work is performed by mold sealing, the work encounters another problem in that the dimensional accuracy between the circuit substrate 2 and a mold is insufficient if serial molding of the circuit substrate is performed. The poor dimensional accuracy results from the difference in thermal expansion coefficient between the substrate 2 and the mold which is caused by the influence of the substrate core 6 of the circuit substrate 2.
On the other hand, as prescribed in JIS-X6303, when the module 1a is to be embedded in or mounted on a base body (omitted from illustration) of the IC card, it is embedded in or mounted on a base body in the form of a laminated card made of a rigid polyvinyl chloride sheet. The module 1a therefore needs to be designed in a simple shape so as to be readily embedded in or mounted on a sheet of the type described above.
Hitherto, when resin-packed ICs are directly embedded in IC cards and are connected to the terminal portions of the IC cards, a problem arises in that connection pins in the ICs can be broken. An undulation can be created over the surfaces of the reverse sides of the IC cards since a plurality of card base bodies are laminated on each other before being pressurized. In order to overcome the above-described problems, additional work needs to be performed to create a recessed portion at a position of the card base body corresponding to a connection pin, or alternatively a connection pin is inserted into the card base body. As described above, when resin-packed ICs and the terminal portions of the IC cards are connected, the shape of the connection portion, in particular the shape of the portion in the vicinity of the pins of the resin-packed ICs' becomes too complicated. This causes a problem in that it is difficult for the resin packed IC in the form of a module to be embedded in or mounted on the IC card base body.